Question

A rectangular room is 6 m long , 5 m wide and 3.5 m high. It has 2 doors of size 1.1 m by 2 m and 3 windows of size 1.5 m by 1.4 m. Find the cost of white washing the walls and the ceiling of the room at the rate of Rs 5.30 per square metre.

Answer 1

area of room=2×h (l+b)
=2×3.5×6×5 =210sq.m
area of one door=1.1×2 = 2.2sq.m
area of two door=2.2×2 = 4.4sq.m
area of one window =1.5×1.4 = 2.1sq.m
area of three window =2.1×3 = 6.3sq.m
area of walls = 210-2.1-6.3
=201.6sq.m
cost of whitewashing the walls =201.6×5.30
=Rs.1068.48

Answer 2

Given,

Length of room = 6 m

Breadth of room = 5 m

Height of room = 3.5 m

So, Area of four walls = 2 (l + b) × h

= 2 (6 + 5) × 3.5

= 77 m²

Area of 2 doors and 3 windows = (2 × 1.1 × 2 + 3 × 1.5 × 1.4)

= (44 + 6.3) m²

= 10.7 m²

Area of ceiling = l × b = 6 × 5 = 30 m²

Thus,

Total area for white washing = (77 – 10.7 + 30) m² = 96.3 m²

Hence, the cost of white washing = ₹(96.3 × 5.30) = ₹510.39

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